Heart valve prosthesis

ABSTRACT

A heart valve prosthesis ( 1 ), including: a stent framework ( 2 ), which can be transferred from a collapsed state into an expanded state, in which the stent framework ( 2 ) extends along an axis (A′), wherein the stent framework ( 2 ) has a plurality of struts ( 20, 24 ), which form a plurality of cells ( 21   a,    21   b,    25 ) connected to one another; and a heart valve ( 3 ), which is fixed to the stent framework ( 2 ). In accordance with the invention, the thickness (d′) of the struts varies in the peripheral direction (U) of the expanded stent framework ( 2 ).

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims benefit of priority to German patent applicationno. DE 10 2016 106 575.7, filed Apr. 11, 2016; the entire content ofwhich is herein incorporated by reference in its entirety.

TECHNICAL FIELD

The invention relates to a heart valve prosthesis, in particular for thetranscutaneous replacement of a heart valve, preferably a mitral valve,secured to an expandable stent framework that varies in thickness in aperipheral direction.

BACKGROUND OF THE INVENTION

Heart valve prostheses as described herein generally have a stentframework, which can be transferred from a collapsed state into anexpanded state and has a plurality of struts, which form a plurality ofcells connected to one another, and also a heart valve (in particularmade of a biological tissue), which is fixed to the stent framework.

When implanting artificial heart valves, in particular a mitral valve,it is necessary for the correct and durable functioning of theartificial heart valve, to adapt the valve to the anatomical environmentin the region of the natural heart valve (annulus). For example, it isnecessary to form the valve asymmetrically in terms of its radialgeometry. Here, the D-shaped annulus geometry of the native valve shouldbe taken into consideration.

On this basis, the object of the present invention is to provide a heartvalve prosthesis which enables an adaptation of this type.

SUMMARY OF THE INVENTION

This object is achieved by a heart valve prosthesis secured to anexpandable stent framework that varies in thickness in the peripheraldirection. Further advantageous embodiments of the invention arespecified and described hereinafter.

In particular, a provision is made in accordance with the invention sothat the thickness of the struts varies in the peripheral direction ofthe stent framework.

Here, the stent framework in the expanded state preferably extends alongan axis, along which the blood of the receiver of the prosthesis flowsthrough an interior of the stent framework defined or surrounded by thestent framework when the prosthesis has been implanted as intended,wherein the stent framework runs around in the peripheral direction ofthe stent framework, which runs around perpendicularly to the aforesaidaxis.

In accordance with a particularly preferred embodiment of the invention,provision is made so that the heart valve prosthesis is configured totake over the function of a native heart valve, wherein the heart valveof the heart valve prosthesis is a mitral valve.

In accordance with a particularly preferred embodiment of the invention,provision is also made so that the thickness of the struts varies in theperipheral direction, in such a way that the stent framework in theexpanded and implanted state has a peripheral cross-sectional contour,which is adapted to the mitral valve annulus of the mitral valve that isto be replaced, wherein the cross-sectional contour is in particularD-shaped.

In other words, in accordance with one embodiment of the invention, thecross-sectional contour in the implanted state has a flattened firstportion and an arcuate second portion connected thereto, wherein theflattened portion extends from the region of the left fibrous trigone tothe region of the right fibrous trigone, based on the expanded andimplanted state of the stent framework.

In accordance with a preferred embodiment of the invention, provision isalso made so that the geometry of the cells of the stent frameworkvaries in the peripheral direction, in such a way that the stentframework in the expanded and implanted state has a peripheralcross-sectional contour which is adapted to the mitral valve annulus ofthe mitral valve that is to be replaced, wherein said cross-sectionalcontour is in particular D-shaped.

Within the scope of this application, a distinction is preferably madebetween three fundamental states for the stent framework: the compressedstate, the expanded state, and the implanted state (also referred tooften hereinafter as the “expanded and implanted state”). The expandedstate is the normal state of the stent framework. This free, expandedstate is adopted by the stent framework in free space without anyinfluence of external forces. In the compressed state, the stentframework is compressed in its radial extent by the influence ofexternal forces. It is in this state that the prosthesis is usuallyintroduced into the body, in particular by means of an insertioncatheter, and is transported to the site of implantation. Withimplantation of the prosthesis, the stent framework re-adopts itsexpanded and now implanted state. The implanted state differs from thefreely expanded state in that the stent framework is disposed in theouter environment of the site of implantation, which acts accordingly onthe expanded stent framework.

The stent framework of this preferred embodiment would adopt a circularcross-section in its pure expanded form. However, the variationaccording to the invention of the thickness of the struts of the stentframework allows the prosthesis or the stent framework to adapt to thenatural cross-section of the mitral valve annulus and to adopt across-section as described above.

In accordance with a particularly preferred embodiment of the invention,provision is made so that the stent framework has first struts whichcome to lie in the region of the left fibrous trigone and in the regionof the right fibrosis trigone, based on the expanded and implanted stateof the stent framework, wherein these first struts have a smallerthickness than the second struts of the stent framework, which come tolie on the mitral valve annulus further away from the left fibroustrigone and the right fibrous trigone.

According to this embodiment a cross-sectional contour is achieved,which consists essentially of a flattened first portion and an arcuatesecond portion connected thereto, wherein the flattened portion extendsfrom the left fibrous trigone to the right fibrous trigone, based on theexpanded and implanted state of the stent framework. If the thinnerfirst struts are positioned at the trigones, the stent framework couldmore easily bend or kink at these positions. Thereby a D-shapedcross-sectional contour is achieved, which corresponds to the naturalgeometry at the mitral annulus. It is not necessary to pre-set aD-shaped cross-sectional contour in the expanded shape, which leads to amuch easier manufacturing process. A D-shaped cross-sectional contour isnaturally achieved in the implanted state of the stent framework.

In accordance with a particularly preferred embodiment of the invention,provision is made so that the stent framework has first struts whichcome to lie in the region of the left fibrous trigone and in the regionof the right fibrous trigone, based on the expanded and implanted stateof the stent framework, wherein the stent framework has a stentstructure that is modified in these regions and which consequently leadsto a local weakening of the radial force of the stent framework.

In accordance with a particularly preferred embodiment of the invention,provision is made so that the stent framework in the region of the leftfibrous trigone and in the region of the right fibrous trigone has anopen cell structure, in which two or more cells are not connected to oneanother.

In accordance with a particularly preferred embodiment of the invention,provision is made so that the stent framework in the region of the leftfibrous trigone and in the region of the right fibrous trigone has amodified cell geometry, in which the size and number of the cells variesin these regions.

In accordance with a preferred embodiment of the invention, provision ismade so that the first struts have a thickness which lies in the regionof 0.5 times to 0.9 times the thickness of the second struts, whereinthe thickness of the first struts is preferably 0.7 times to 0.9 times,in particular 0.8 times the thickness of the second struts.

The struts of the stent framework in accordance with an embodiment ofthe invention are preferably integrally connected to one another orintegrally formed on one another via connection regions.

In accordance with a preferred embodiment of the invention, provision isalso made so that the first struts form two cells of the stentframework, which are arranged adjacently or above one another in thedirection of the axis of the stent framework and are connected to oneanother via a connection region, wherein said two cells come to lie inthe region of the left fibrous trigone, based on the expanded andimplanted state of the stent framework.

In accordance with a preferred embodiment of the invention, provision isalso made so that the connection region has a first and a second edgeportion, wherein the two edge portions lie opposite one another in theperipheral direction when a stent framework is expanded, wherein arecess is formed in each edge portion, and wherein the two recesses arearranged offset relative to one another in the direction of said axis ofthe stent framework.

In accordance with a preferred embodiment of the invention, provision ismade similarly so that the first struts form two further cells of thestent framework, which are arranged adjacently or above one another inthe direction of said axis and are connected to one another via afurther connection region, wherein said two further cells come to lie inthe region of the right fibrous trigone, based on the expanded andimplanted stated the stent framework.

In accordance with a preferred embodiment of the invention, provision isalso made so that the further connection region has a first and a secondedge portion, wherein the two edge portions lie opposite one another inthe peripheral direction, wherein a recess is formed in each edgeportion, and wherein the two recesses are arranged offset relative toone another in the direction of the axis.

The smaller thicknesses of the struts in the region of the left andright trigone and also the above-described thinning of the connectionregions of the thinner struts or cells advantageously enable or promotea deformation of the expanded stent framework, wherein the stentframework has the geometry or cross-sectional contour adapted to themitral valve annulus (in particular D-shaped cross-sectional contour).

In accordance with a preferred embodiment of the invention, provision isalso made so that the stent framework has a peripheral first edgeregion, which surrounds an inflow tract of the heart valve prosthesis,via which blood can flow into the heart valve prosthesis, and also anopposite peripheral second edge region, which defines an outflow tractof the heart valve prosthesis, via which blood can flow out from theheart valve prosthesis.

In accordance with a preferred embodiment of the invention, provision isalso made so that the stent framework at the outflow tract has loops foranchoring the heart valve prosthesis to the cusps of the native mitralvalve.

In accordance with a preferred embodiment of the invention, two loopsare preferably provided in this respect, which are configured to anchorthe heart valve prosthesis to the anterior cusp of the native mitralvalve.

Here, provision is preferably made so that these two loops run inopposite directions starting from the stent framework, wherein each loopruns in the direction of an assigned trigone of the native mitral valve.

In accordance with a further embodiment of the invention, a further loop(in particular just one) is preferably provided, which is configured toanchor the heart valve prosthesis to the posterior cusp of the nativemitral valve, wherein the further loop is shorter in its extensiondirection than the two loops for the anterior cusp. The length of thisfurther loop is preferably 0.7 to 0.8 times, preferably 0.75 times thelength of the two other loops.

In accordance with a preferred embodiment of the invention, provision isalso made so that the stent framework has cells for anchoring the heartvalve prosthesis to the outflow tract, which cells are curved outwardly.

In accordance with a preferred embodiment of the invention, provision isalso made so that the stent framework has shortened cells on aperipheral edge of an inflow tract of the stent framework, the length ofsaid cells in the direction of said axis of the (expanded) stentframework being shorter than the length of cells of the stent frameworkthat are adjacent in the peripheral direction, wherein the shortenedcells are configured to come to lie in the region of the aortic peak ofthe native mitral valve in the expanded and implanted state of the stentframework.

In accordance with a preferred embodiment of the invention, provision isalso made so that the heart valve prosthesis is configured to beimplanted minimally invasively by means of a catheter.

In accordance with a preferred embodiment of the invention, provision isalso made so that the stent framework is expandable (example by means ofa balloon), preferably is self-expanding. In the latter case, the stentframework deploys automatically as soon as it is released by thecatheter used for implantation, which transports the stent framework inthe compressed state to the site of implantation.

DESCRIPTION OF THE DRAWINGS

Further features and advantages of the invention will be explained inthe description of the drawings of exemplary embodiments of theinvention, which is provided with reference to the drawings as follows.

FIG. 1 shows schematic views of a mitral valve.

FIG. 2 shows a stent framework of a heart valve prosthesis according tothe invention in a state spread out flat.

FIG. 3 shows a schematic illustration of a heart valve prosthesisaccording to the invention in an implanted state.

FIG. 4 shows a further schematic illustration of a heart valveprosthesis according to the invention in an implanted state.

FIG. 5 shows a schematic view of a heart valve prosthesis according tothe invention.

FIG. 6 shows a schematic view of a further stent framework of a heartvalve prosthesis according to the invention in a state spread out flat.

DETAILED DESCRIPTION

FIG. 1 shows views of a mitral valve M. The heart valve prosthesis 1according to the invention is in particular configured to replace afaulty valve M of this type, wherein the prosthesis is displacedlaterally by a stent framework 2 of the heart valve prosthesis. Themitral valve annulus Ma forming accordingly has a D-shaped geometry,wherein the stent framework 2 obtains the geometry in the region of theannulus Ma as a result of the provision of struts 20, which inparticular are thinner. More specifically, A1 to A3 denote the portionsof the anterior valve cusp A, whereas P1 to P3 denote the portions ofthe posterior valve cusp P. Furthermore, the aortic peak AP and also theleft and right fibrous trigone Tr1, Tr2 are shown.

A cut view of a stent framework 2 according to the invention for thestructure of a mitral valve prosthesis 1 is illustrated in FIG. 2. Thestent framework 2 has three anchors 100 for the fastening of thecommissures of the artificial valve cusps, which are not illustratedhere, and also preferably a total of 18 cells 20 and 24 running aroundradially, wherein the lower part of the stent cells 20 can be providedwith extensions, to which additional retaining loops 28, 29 (for examplesee FIGS. 3 and 4) can be attached. On the whole, the stent cells 20, 24in this embodiment can be arranged above one another in particular infour rows, and can thus form the stent framework 2 as a whole. What aredecisive for obtaining a D-shaped geometry, as mentioned at the outset,are struts 20, 24 of different thickness, which after implantation cometo lie in the region of the trigones Tr1, Tr2 (see also FIG. 1), at eachof which a region of greatest bend of the cross-sectional contour 23 ofthe expanded stent framework 2 is present (in the implanted and expandedstate the left vertical edge of the cut form is connected to the rightedge of the cut form, such that a stent framework 2 is formedaccordingly, which extends along a central axis A′ and runs aroundtransversely thereto in a peripheral direction U, wherein the stentframework 2 (based on the axis A′) forms an inflow tract 31 and anoutflow tract 27 at the upper and lower ends respectively).

In order to achieve a suitable curvature of the stent framework 2, thestent thickness d′ of the first stent 20 can be 0.8*d compared to thesecond stent 24 for example, wherein d specifies the thickness of thestruts 24 in all other regions (away from the trigones Tr1, Tr2).

In addition to the thinner stent struts 20, the connection regions 26 band 26 a (not shown) of the individual (thinner) stent cells 21 a, 21 bare flexible. This makes it possible for the stent geometry to betterfollow the natural mitral geometry and thus anchor the artificial heartvalve better in the annulus Ma.

For this purpose, provision is preferably made for example so that thecorresponding connection region 26 b (or 26 a) of the thinner stent 20has a first and a second edge portion 210, 211, wherein the two edgeportions 210, 211 lie opposite one another in the peripheral direction Uof the stent framework 2, wherein a recess 212 is formed in each edgepotion 210, 211, wherein the two recesses 212 are arranged offsetrelative to one another in the direction of the axis A′ of the stentframework 2.

For the fixing of the valve 1, loop structures 28 are also preferablyattached to the outflow tract 27. Here, two anterior loops 28, forexample according to FIG. 3, are attached for the fixing of the anteriorcusp A. Here, the loops 28 run from the commissure mounting 100 in thedirection of the trigones Tr1, Tr2 so as to be able to be supportedthere. These loops 28 running at an incline are intended in particularto reduce a hooking with the chordae tendineae CT during implantation.Just one posterior loop 29 is provided in the region of the posteriorcusp P (see FIG. 4). This is preferably formed such that it covers thegreatest possible area of the cusp P in the distal loop region, withoutbecoming hooked with the chordae tendineae CT during the positioning ofthe loop 29. Furthermore, the posterior loop 29 is preferably shortenedand corresponds in this example approximately to 0.75 times the lengthof the anterior loop 28.

What is important for the fixing of the artificial mitral valve 1 is theanchoring with the native cusps (denoted in FIG. 1 by A for anteriorcusp and by P for posterior cusp). This can be provided generally by useof large loops (see also FIGS. 3 and 4), which are attached in theoutflow tract 27 of the heart valve 1. It is also possible according toFIG. 5 to design the cell geometry such that part 30 of the cell-formingstruts 40 can be curved outwardly. The remaining part of the struts 40then forms the respective cell. It is thus possible to provide anadditional anchoring mechanism in the outflow tract 27 of the stentframework 2, which anchoring mechanism protects the artificial valve 1against a possible dislocation.

A further cut view of a stent framework 2 is shown in FIG. 6, the stentframework having been adapted to the asymmetrical conditions in theregion of the mitral annulus (for example by use of the above-describedthinner struts 20). The cells 33 are also shortened at the edge 310 ofthe inflow tract 31 in the region of the aortic peak AP (see FIG. 1)compared to the adjacent cells 34 on either side. Furthermore, theintegrated retaining loops 28, 29 again have a different length in thedirection of the axis A′. The retaining posterior loop 29 of theposterior cusp P is thus shorter than the two retaining anterior loops28 of the anterior cusp A. The posterior loop 29 is for example 0.75times as long here as the corresponding anterior loop 28. Here, itshould be noted that an asymmetric D-shape can be impressed on the stentframework 2 in FIG. 4, also with heatsetting. In contrast thereto, thestent framework 2 in FIG. 2 can have a radially symmetrical startingform in the pure expanded state, wherein it can adapt to the D-shape ofthe natural mitral annulus M on account of the different mechanicalproperties of the stent framework 2 (caused by the struts 20, 24 ofdifferent thickness or the connection regions 26 a, 26 b).

It will be apparent to those skilled in the art that numerousmodifications and variations of the described examples and embodimentsare possible in light of the above teaching. The disclosed examples andembodiments may include some or all of the features disclosed herein.Therefore, it is the intent to cover all such modifications andalternate embodiments as may come within the true scope of thisinvention.

What is claimed is:
 1. A heart valve prosthesis (1), comprising: a stentframework (2), which can be transferred from a collapsed state into anexpanded state, in which the stent framework (2) extends along an axis(A′), wherein the stent framework (2) has a plurality of struts (20,24), which form a plurality of cells (21 a, 21 b, 25) connected to oneanother, and a heart valve (3), which is secured to the stent framework(2), characterized in that the thickness (d′) of the struts varies in aperipheral direction (U).
 2. The heart valve prosthesis according toclaim 1, characterized in that the heart valve prosthesis (1) isconfigured to take on a function of a native mitral valve (M), whereinthe heart valve (3) of the heart valve prosthesis (1) is a mitral valve(3).
 3. The heart valve prosthesis according to claim 1, characterizedin that the thickness (d, d′) of the struts (20, 24) varies in theperipheral direction (U), in such a way that the stent framework (2) inthe expanded and implanted state has a peripheral cross-sectionalcontour (23) which is adapted to the mitral valve annulus (Ma) of themitral valve (M) that is to be replaced.
 4. The heart valve prosthesisaccording to claim 3, characterized in that a cross-sectional contour(23) consists essentially of a flattened first portion (23 a) and anarcuate second portion (23 b) connected thereto, wherein the flattenedportion (23 a) extends from a left fibrous trigone (Tr1) to a rightfibrous trigone (Tr2), based on the expanded and implanted state of thestent framework (2).
 5. The heart valve prosthesis according to claim 1,characterized in that the stent framework (2) comprises first struts(20), which come to lie in a region of a left fibrous trigone (Tr1) andin a region of a right fibrous trigone (Tr2), based on an expanded andimplanted state of the stent framework (2), wherein the first struts(20) have a smaller thickness (d′) than second struts (24) of the stentframework (2), which come to lie on a mitral valve annulus (Ma) furtheraway from the left fibrous trigone (Tr1) and the right fibrous trigone(Tr2).
 6. The heart valve prosthesis according to claim 5, characterizedin that the first struts (20) have a thickness (d′) which lies in aregion of 0.5 times to 0.9 times the thickness (d) of the second struts(24), wherein the thickness (d′) of the first struts (20) is optionally0.8 times the thickness (d) of the second struts (24).
 7. The heartvalve prosthesis according to claim 5, characterized in that the firststruts (20) form two cells (21 a) of the stent framework, which arearranged adjacently in a direction of the axis (A′) and are connected toone another via a connection region (26 a), wherein the two cells (21 a)come to lie in the region of the left fibrous trigone (Tr1), based onthe expanded and implanted state of the stent framework (2).
 8. Theheart valve prosthesis according to claim 7, characterized in that theconnection region (26 a) has a first and a second edge portion (210,211), wherein the two edge portions (210, 211) lie opposite one anotherin the peripheral direction (U), wherein a recess (212) is formed ineach edge portion (210, 211), and wherein the two recesses (212) arearranged offset relative to one another in the direction of the axis(A).
 9. The heart valve prosthesis according to claim 5, characterizedin that the first struts (20) form two further cells (21 b) of the stentframework (2), which are arranged adjacently in a direction of the axis(A′) and are connected to one another via a further connection region(26 b), wherein the two further cells (21 b) come to lie in the regionof the right fibrous trigone (Tr2), based on the expanded and implantedstate of the stent framework (2).
 10. The heart valve prosthesisaccording to claim 9, characterized in that the further connectionregion (26 b) has a first and a second edge portion (210, 211), whereinthe two edge portions (210, 211) lie opposite one another in theperipheral direction (U), wherein a recess (212) is formed in each edgeportion (210, 211), and wherein the two recesses (212) are arrangedoffset relative to one another in the direction of the axis (A′). 11.The heart valve prosthesis according to claim 1, characterized in thatthe stent framework (2), in order to allow blood to flow out, defines anoutflow tract (27), wherein the stent framework (2) at the outflow tract(27) has loops (28, 29) for anchoring the heart valve prosthesis (1) atanterior and posterior cusps (A, P) of a native mitral valve (M),wherein two anterior loops (28) are optionally provided, which areconfigured to anchor the heart valve prosthesis (1) at the anterior cusp(A) of the native mitral valve (M), and a posterior loop (29) isoptionally configured to anchor the heart valve prosthesis (1) at theposterior cusp (P) of the native mitral valve (M), wherein the posteriorloop (29) is shorter than the two anterior loops (28) for the anteriorcusp (A).
 12. The heart valve prosthesis according to claim 1,characterized in that the stent framework (2) has cells (30) at anoutflow tract (27) for anchoring the heart valve prosthesis (1), whereinthe cells (30) are curved outwardly.
 13. The heart valve prosthesisaccording to claim 1, characterized in that the stent framework (2) hasshortened cells (33) on a peripheral edge (310) of an inflow tract (31)of the stent framework (2), wherein the length of the shortened cells(33) is shorter in a direction of the axis (A′) than the length ofperipheral cells (34) that are adjacent in the peripheral direction (U),wherein the shortened cells (33) are configured to come to lie in aregion of an aortic peak (AP) of a native mitral valve (M) in theexpanded and implanted state of the stent framework (2).
 14. The heartvalve prosthesis according to claim 1, characterized in that the stentframework (2) is expandable, optionally self-expanding.
 15. The heartvalve prosthesis according to claim 1, characterized in that the heartvalve prosthesis (1) is configured to be implanted by means of acatheter.